Automatic iris for cameras



July 7, 1931. w, MYERS ETAL 1,813,635

AUTOMATIC IRIS FOR CAMERAS Filed March 27. 1930 2 Sheets-Sheet l INVENTOR. Z5229 M fi/Ies a; 10.70 ra 570 /6 5 & me 170,97 :70 gr:

A TTORNE Y.

July 7, 1931. J. w. MYERS ETAL 1,813,635

AUTOMATIC IRIS FOR CAMERAS Filed March 27, 1930 2 Sheets-Sheet 2 i i O 1 I I 4 I I I I A TTORNE Y.

Patented July 7, 1931 UNITED STATES [PATENT orrlca JOSEPH W. MYERS AND BOLAii'D J. WILKINSON, OF JACKSON, IICmGAI AUTOMATIC IBIS FOB CAMERAS Application filed March 27,1930. Serial 110. 489,478. '1

Our invention relates to an automatic iris for cameras and an object of our improve ments is to provide means for automatically adj usting'the light aperture so that the image '6 upon the film shall have a constant intensity, evenwhen the light upon the object being photographed is varying. We accomplish this object in the apparatus shown in the accompanying drawing, in which:

Figure 1 is a plan view of an apparatus embodying our invention and so much of a camera as is necessary to illustrate its connection therewith.

Figure 2 is a front view of the same.

Figure 3 is an elevation of the right hand portion of Figure 1, the apparatus being turned around so that what is in the back in Figure 1 is brought to the front so that it ma be seen by the observer. l igure 4 is a section on the line IV, IV,

Fi re 2. I

igure 5 is a section on the line V, V, FigureA.

Figure 6 is a diagrammatic view illustrating the operation of the device.

Figure 7 is a partial side view,0f the apparatus. The tube 5 being shown in section.

2 is a camera. 3 is a casing secured by an attaching device 23 to the camera 2. In the casing 8 is the lens-tube 4 for the camera and below [and parallel to this a second tube 5 having a lens therein.

6, 6 are apparatus of the DArsonval galvanometer type adapted to rotate shafts 6a, 6a an angular distance that is a function of the current of electricity passing through them. 'An apparatus 6 is located within the casing 3 at each end thereof and has an arm 7 or 8 secured'upon its shaft 6a. The arm 8 has at its end, remote from the lens-tube 4, a pointer 8a. 3a is a slot having a graduated scale, as shownin Figure. 3, through which the ointer 8a may be observed.

e arms 7 and 8 extend toward each other, their adjacent ends being paralleL and overlapping andat these adjacent ends, provided with notches 7 b and 86 that coact with each other to define the aperture for the light through the'lens-tube. I have shown these each other and together forming a square I opening, as shown in Figure 5, which has its area varied but retains its shape when the a arms 7 and 8 have their adjacent ends moved relative to each other. 12 is a light-sensitive cell located at the inner end of the tube 5 in position to receive the light passing through the lens in said tube. Referring to the diagram of Figure 6, 9 is a source of electricity and 11 indicates a circuit through the apparatus 6, 6 and the selenium cell 12. 10 is a construction for regulating the current in the circuit 11. This may have a switch 10a breaking the circuit. 13 is the film upon which the image is formed.

The operation of the above described device is as follows:

The camera being directed on the object to be photographed, the light from said object passes equally into the tubes 4 and 5..' The light passing into the tube. 5 acts upon the light-sensitive cell 12 so that the current passing through the circuit 11 and the 8P? paratus 6, 6 will be regulated thereby to vary the angles of the arms 7 and 8 and thus regulate the openings between the notches 7b and 8b to compensate for any variation in the light from the object being photographed. As this light varies the current will vary accordingly and the light aperture will be thereby adjusted to the light so as to maintain a constant intensity of image upon the film 10.

A filter may be used, if required, to adjust the sensitiveness of the light-sensitive cell to the requirement of the apparatus.

To adjust the apparatusshown so that it will function as intended it is necessary to train the cellon a light of known intensity and then by means of the. potentiometer 10 to regulate the current through the motors so that the diaphragm opening is proper for this known intensity.- The known intensity may be north sky light which is fairly constant or it may be a flash fixed source. The diaphragm openin existing at any time may be readily o rved through the small window 3a in the apparaslots as having their walls at right angles to tus shown, behind which a pointer 8w motilight bulb operating at known brilliancy or any other'reasonably two means adapted to vary vated from one of the motors operating the dia hragm is placed.

e lenses are arranged so that substantiall the same image is formed at 12 and 13. T e apparatus 6, 6 are designed so that .they shall actuate the arms 7 and 8 to ally actuated means for the purpose described.

2. ,Thecombination of an apparatus adapted to va electrical y actuated means for operating said apparatus and a light sensitive means ada ed to vary the current in said electrica actuated. means forthe purpose-describe said light sensitive means being so located that it is exposed to'light of the same .intensity as that passing to the objective aperture.

3.-' The combination of an apparatus adaptthe area of the, light aperture, an.

8. The combination of apparatus ed to vary the area of the light aperture, m electrically actuated means for operating said apparatus and a light sensitive means adapte to vary the current in said electrical- 1 actuated means forthe purpose described,

t e same forming a unit adaptedto be'atv tached or removed from' the camera "as a whole. a I

9. The combination of apparatus for varying the intensityof the image, a light sensitive means adapted to actuatesaid apparatus for the ur ose described and means for causing t e light from the field of view'taken .in by the ob ective to also fall on-the' light sensltive ortion of said actuatin means and to limit esame to'that field o view.

fication.

JOSEPH W. MYERS.

ROLAND J .WILKINSOH ed to vary the areaof the light aperture and an electric motor having specially formed pole ieces, for actuating said apparatus where y said apparatus varies the area of the light perture to adapt it to the intensity of the light being received.

4. The 4 combination of paratus adapted to vary the area of the l aperture, an electrically actuated means for operating said ap aratus and alight sensitive means adapte to vary the current in said electrically actuated means for the purpose described and an indicator, showing the area of the openin at any time. 7

, 5. The com ination of an adjustable a paratus adapted to vary the area of the liglit aperture, an electrically actuated means for operating said apparatus and .-a light sensithe current in an adjustable aig t In testimony whereof, we sign this specisaid electrically actuated means for the pu'rpose described and meansfor adjusting the current .through said' electrically actuated means at will so that'it shall varywithin limits required by the use.

6. The combination of anadjustable a paratus ada' ted to vary the area of the light aperture, a

means adapte to vary the currentthrough .said motor for the purpose described. a

7. The OOIIIblIIEtIOII'Of two movable arm's adapted to vary the area, of .the li ht aperati lTA ture'by their re ve movement, a rsonval type motor for each of said arms and a.

light-sensitive meansadapted to vary the current through. said motor for the purpose described.

p Arsonval type of motor for actuatmg said a paratus and a light-sensitive 

